Bags made of flexible material have been used since antiquity for the storage and dispensing of fluids. Wine and water storage bags made from animal skins are still in use, just as they were in antiquity. Latex rubber bags with attached hoses and probes found early use administering enemas in the medical field. All such bags have openings formed in them during manufacture for manually filling the bag with liquid, as well as for dispensing it.
In 1969 Baxter Laboratories introduced the first intravenous formula storage and dispensing bag. This bag differed from conventional bags in that the fluid was introduced in the manufacturing process and the bag was then sealed and sterilized for shipment to the customer. The bag offered a number of advantages over glass bottles previously used for this purpose. It was lighter, stronger and more compact, making it easier to ship and store. Because it was collapsible, it did not require a separate venting mechanism to allow air to enter as it was emptied. Elimination of the vent simplified the emptying process. No vent was needed in the administration set bag connector, either, and inadvertent administration of air to the patient was prevented.
The liquid formula in these prior art intravenous formula bags was normally dispensed with a dispensing spike which was forced through a dispensing port structure on the bag. The port structure was sealed into the bag during manufacture by laminating it between the two sheets of plastic film from which the bag was constructed. The port structure normally comprised a rigid plastic tube having an internal lumen obstructed by a thin, molded plastic septum. The spike, which was molded of rigid plastic, was used to puncture the septum. Fluid could then flow out of the bag through the spike. The spike was held in place by a friction fit in the lumen.
Generally, such a spike would be a component of an administration set designed to deliver the fluid to a patient or to some other container, or location, for use. In its most common form, the spike is connected to a length of plastic tubing. The tubing normally terminates with a connector designed to facilitate final delivery. In the case of an intravenous solution, the administration set connector is usually designed to be connected to a needle.
Incorporating a port in a bag in the aforedescribed manner remains the most common method of fabrication today. The method is effective, but relatively costly because of the need for a separate port structure and a secondary fabrication operation to seal the port structure between the two film layers of the bag. In addition, the seal area around the port structure has a tendency to leak.
Attempts have been made to improve dispensing systems for sealed bags by gluing a port structure to the outer surface of a bag. Such a system is illustrated in the Kuhn et al. U.S. Pat. Nos. Des. 361,838 and 338,726. In this system, the port structure has no internal septum, i.e., the bag wall is punctured by a dispensing spike. This greatly simplifies the fabrication of the bag because no port structure need be incorporated during fabrication. The elimination of a port structure which must be assembled with the bag is especially important with modern bag manufacturing technology where bags are formed, filled and sealed in a continuous, high speed process. By gluing the port structure onto the bag surface after forming, filling and sealing, manufacturing problems are greatly reduced. However, this system still requires a separate port structure, and an additional operation is needed to attach it to the bag by gluing, for example.
In the aforedescribed prior art systems the dispensing spikes are similar. They each have a sharp, piercing tip on one end of an elongated spike body containing a fluid passage. There is a very slight taper from the tip to a flange surrounding the body, and spaced from the tip, which serves as a stop. Retention, and a tight, non-leaking fit, are obtained by the friction fit of the spike body in the port structure. In one case, the spike pierces the bag wall itself. In the other case, the spike pierces a septum in the port structure.